1. Field of the Invention
This invention relates to earth boring bits--especially to improvements to the nozzle retention systems used to direct high velocity streams of drilling fluid against the borehole.
2. Description of the Prior Art
Among the several nozzles retention systems used to removably retain wear resistant nozzles in the bodies of earth boring bits is the snap ring retainer. Here, a snap ring registers with a so-called snap ring groove in the nozzle passage and retains a wear resistant, usually tungsten carbide, nozzle in the body of a drill bit.
Snap ring nozzle retention systems have been commercially successful for decades--but they have occasional problems. One problem arises due to the abrasives commonly found in drilling fluids and the turbulent flow in the cavity surrounding the nozzles of a drill bit. Under extreme conditions the resulting abrasive wear is sufficient to erode the snap ring "eyes" (plier receptacles) to a degree that prevents convenient removal of the snap ring and the associated nozzle. During the worst conditions, the snap ring is eroded until the nozzle is washed from the nozzle passage. Then, the efficiency of drilling decreases--sometimes drastically--due to the resulting decrease in the velocity of the fluid stream impinging against the borehole.